The present invention relates to a steel strip descaling apparatus and a steel strip manufacturing apparatus using the descaling apparatus.
A technique that removes an oxide (scale) formed on the surface of steel strips by electrolyzing scale in solutions such as a neutral salt, a nitrate and a sulfate is known.
The Japanese patent Laid-open No. 3-56699 describes pumping an electrolyte to a steel strip submerged in the electrolyte from the hole of an electrolyte in order to prevent the steel strip from waving.
The Japanese patent Laid-open No. 8-100299 describes spraying an electrolyte to a steel strip in the air in order to apply an electric current.
However, in the art of No. 3-56699, because electrolyte and an electric conductor do not contact each other directly, a large quantity of electrolyte is necessary. The apparatus is large because of a large electrolyte bath. As the electrodes are also located in the electrolyte, a third disadvantage of this prior art technique is that short circuits occur among the electrodes through the electrolyte.
In the art of No. 8-100299, because whirls occur between an electrode and the steel strip, electric current provided to the steel strip from the electrodes is small and the electric current is variable. Therefore the steel strip is not descaled rapidly and uniformly because of the variable electric current. We can not produce a steel strip which has uniformly beautiful surfaces with this art.
The present invention relates to a steel strip descaling apparatus and a steel strip manufacturing apparatus.
The purpose of the present invention is to provide the steel strip descaling apparatus and the steel strip manufacturing apparatus which improve the electric power efficiency, processing speed and miniaturization.
To achieve the above purpose, a feature of the present invention is that electrodes have jet openings which jet the electrolyte to the steel strip, that is to say, the electrode is integrated with the nozzle which jets an electrolyte.
With these electrodes, by jetting the electrolyte to the steel strip in the air and applying a voltage to the electrode, the scale (oxide coating or layer)on the surface of the steel strip is removed.
According to a feature of the present invention, it is possible to reduce the size of an electrolyte tank storing the electrolyte, because the quantity of an electrolyte decreases by jetting the electrolyte in the air. Therefore, the descaling apparatus is miniaturized.
In contrast to the conventional art wherein the steel to be treated is submerged in the electrolyte, the present invention""s use of jetting means for jetting the electrolyte onto the steel strip obviates immersion of the steel strip and the occurrence of short-circuit electric current between the electrodes, thus improving electric power efficiency.
Because the electrolyte jetted from the jet opening contacts an conductor applied the voltage, we can supply large electric current to the steel strip through the jetted electrolyte.
Therefore, the electric current density of the steel strip is large and the steel strip is descaled rapidly.
Providing many electrodes improves the speed of the descaling because the electric current density in the steel strip increases.
Another feature of the present invention is that the descaling apparatus further has force adjustment of the jetted electrolyte.
By adjusting the force of the jetted electrolyte, the waving and the flexure of the steel strip is prevented, and we can arrange the electrodes close to the steel strip.
Because the electrodes are moved closer to the steel strip, a voltage drop between the electrodes and the steel strip becomes lower, and the electric power for the descaling can be decreased.
By using the above-mentioned descaling apparatus, the steel strip manufacturing apparatus attains an improvement in electric power efficiency and the processing speed, and the manufacturing apparatus becomes small.